Apparatus for expanding perlite



July 15 1952 G. H. MCDONALD 2,603,471

APPARATUS FOR EXPANDING PERLITE Filed Aug. 8, 1947 2 SHEETSf-SHEET l G. H. McDoNALD APPARATUS FOR EXPANDING PERLIT July 15, 1952 2 ASHEETS-SHEET 2` Filed Aug. 8, 19.47

FINES TO CYCLONE ExFoL/A rfa IN1/mm1; v Gemme/ Mae/ma Patented July 15, 1952 2,603,471 APPARATUS Foa EXPANDING PERLITE- George H. McDonald, Long Beach, Calif. ApplicationAugust 8, 1947, Serial No. 767,452

f My invention relates to a method of and means for preparing materials from naturally occurring yvolcanic glasses which'when heated under controlled conditions form masses'several'times the volume of the original ',nfiaterial.v

The natural mineral 'generally designated as perlite is Aan aluminum silicate vusually containing less than 8% of combined sodium potassium and calcium oxides,`less than 3% iron and other elements, 2.5 to vcombined. water, and the remainder silica plus alumina. Perlite'as herein referred to may be defined as a spherulitic yobsidian; a silicous volcanic glass, which cooled rapidly from a molten state under vsuch condi-v ltions governing incipent crystallization as to form a mass of more or less concentric spheroids.

I he raw material, if rapidly heated to between l500 F. and 18G0 F., exfoliates or expands into a tumescent mass of minute cells, each lenclosed in an envelope of glassyl material, and in this form is a valuable material because of itsheat insulation, sound absorbent, fire and chemical resistant, and low moisture absorbent characteristics, and for its value in formingl a light weightY aggregate with plaster or light weight cement.`

The manner in which heating is carried out'is critical', since if heating isv not uniform the surface of some particles vmayv melt beforev the interior of the material' is s uicientlyheated vto have yassumed the desired cellular structure, while with some particles the'steam and gases generated 2 may escape slowly leaving' lmerely a'stiokyg-useless mass. In either eventthe end product is not a homogeneous tumescent'material. ".By the use of the present invention the 'end product' may be considered a synthetic pumice; bothpumiceland perlite treated in the manner of the' present invention are the same general type o f-f magma subjected to 'heat and sudden release of` pressure.

'Explosive volcanic eruptionr in the caseoffnatural pumice and controlled heating with expansion of contained water vapor andfgases in the caseof processed perlite. L

t is an object of my invention to provide a method for heat treating perlite Aand other ores which ensures that each piece ofv ore is heated .on all sides-with acontrolled flame bringing it to the proper temperature at apredetermined rate of heating.

It is a further object of the invention 'torprovide a furnace for heating Vperlite whichis provided with overhead gas .outletsplaying ame downwardly on individual piecesl ofthe ore which are so supported that the llame/flows over the ore on all sides, thus thoroughly and evenly-heat- Achims. (cieca-21) une sof Fig. 1':l 4

ing `the pieces of material to a predetermined :temperature. 1 a

It is a still further object-'of the invention to provide a method of heat treating perlite and other ores which, in addition to ensuring that the ore is fully treated undercontrolled conditions provides the treated vmaterial free from fines and dust. f

Yet another object of the invention is to provide a furnace for inducing intumescence of perlite and similar mineral ores which is capable of continuous operation .to securepm'aximum output.

Another object .of the4v invention. is to 'providea -furnace construction for 'inducing' intumescence of perlitexand similar 'ores which lmeans are provided for adjusting the conditions of combustion within the furnaceby the introduction of a combustible mixturewitli or without additional medium under controlled conditions, thus enabling ores of different characteristics to be treated with maximum` efficiency. y g

Still another objectv of the invention is to provide a furnace construction provided with means for Vsupplying Asized piecesof ore,l to the furnace bed in spaced relation and providing means for playing flame` aroundeach piece of the ore.

Still further objects and-features of the invention will hereinafter appear from the followingv description of the invention taken inconjunction with the accompanying drawings.

In the drawings: y f

Fig. 1 is a side elevation of a furnace unitwith parts shown in section and certainupwardly eX- tendng parts broken away -to shorten'thefguri??A v' Fig. 2 is a fragmentary plan view ofthe lfurnace with parts shownin' section; f f

Fig. 3 is a fragment face view-of the control panel for one furnace of the unit; a f

f Fig. 4 is a fragmentary detail in section to an enlarged scale, showing afuel controlvalve;

Fig. V5 is a view ofthe .aparts shown in Fig. 4

looking in the directionofthe arrows 5 in that f gure: f 1

Fig. 6 is a section to an enlarged scalefon the Fig.:7 is asectionon the lines 1-1 of Fig. 2; Fig. 8 is a section onL the line 8-8 of Fig.v 2; Fig.j9 lis asection togan enlarged scale on vthe line 9-9 of Fig. 8. y

. -In the drawings, the

' -framework of vertical tubular members arranged in a circle Aand connectedfby radial struts both above and below the annular bed I'2 of Ithe furnace f rnumeral'lll indicates a j vwardly upon the pieces of material.

which is supported on a ring ange I4 which in turn is welded to bearing arms I6 rigidly connected to a bearing structure I8.

The bearing structure is supported on a tubular structure 20 enclosing the drive gears rotating the furnace bed and driven by a motor 22 through reduction gears in housing 24. Obviously, any suitable arrangement of framework and rotary` drive for the furnace bed may be utilized and no more detailed description thereof is thought necessary.

The furnace bed l2 may be formed of a fiat annulus of refractory material such as fire clay,

preferably reinforced by expanded metal or the like indicated at 26.

The furnace bed is covered by a .stationary housing 28 secured to an annular plate30 mounted on the upper radial struts of the frames, the housing having the outline shown in Fig. '7.

In order to secure maximum output, I prefer to arrange a plurality of separate furnace sections 32, four such sections being incorporated inthe described embodiment of the invention, but itis to be understood that while this arrangemeit is preferred to me, any. other arrangement of the furnace sections may be made, either as a single unit, or series of units and with the units arranged in desired .combinations. A

Each furnace unit includes a feeding element 34 arranged to receive previously sized material.

as shown in Fig. 9, and deposit the material in a series of separate pieces simultaneously upon the furnace bed and spaced from one another. Each feeding element inclu'desva drum 35 having its Asurface provided with aligned pockets 33. The bottom 40 of the 'hopper is provided with slots aligned with a row of pockets in the drum, the pieces of material falling through tubular guides 4| onto the furnace bed. The drum is continu- Iously rotatedby' shaft 42 supported at its outer end in a wall of the housing and at its inner end in a small central housing secured to the upper radial struts `and affording an upper bearing to a centrally arranged vertical shaft 44 secured to 'the rotating supporting frame of the furnace bed. A bevel gear 46 is secured to the upper end of shaft 44 and bevel pinions 48V mounted on the inner vend of shafts 42 mesh with gear 46 and cause rotation of drums 36 as bevel gear 46 is'rotated by the rotation of the furnace bed'support. l The furnace bed is rotated in the direction of the arrow in Filg.l2, so that the pieces of the material are next carried under a set of burners arranged in a denite pattern in each furnace unit and playing a hot carefully controlled fiame down- The first group in each set of burners is supplied through vpipe 5D with ran Vair'gas mixture which delivers into a manifold chamber 52 provided with a double line'of holes 54 extending radially across the chamber 52 adjacent itsforward wall, the holes being Aaligned with Vthe pieces of material posil tioned on 'the furnace bed by the chutes or guide tubes 4|. The flames extend from each hole from the lower face of the manifold Vvertically upon the pieces of material and supply a preheat'thereto-which I have found beneficial in enabling the 'material to acquire an vinitialcharge of heat and 'absorb it during passage of the Vmaterial under 1 the unperforated portion of the bottom of the preheat manifold. It is evidentthat I may-prefer t'o omit the preheat stage or to add additional heating orifices in place of a' restricted number laccording to the vcharacte'rof the treatment most suitable to a particular type of material,l since volcanic glasses vary considerably. Y

The material next passes under flames projected downwardly from orifices 56 formed in the bottom of manifold chamber 58 supplied by fuel pipes 60. The manifold chamber is preferably provided with both horizontal and vertical walls to effect even distribution of the fuel to all the orifices 56. The gaseous fuel is supplied under pressure by means of a blower 62 associated with each gas pipe, the gas being fed into the blower casing and air introduced into the casing through an adjustable valve 64 of the usual form, as shown in Fig. 5. Both the gas and air feeds are controlled by rods carried to a control panel 55 and fitted with control knobs 68 provided with indicators moving over a scale so that the setting of the valves may be made accurately.

Preferably, I provide conduits 10 tapped into the gas pipes or blower casings and separately controlled whereby additional elements may be supplied to the furnace chambers'to control the character of the combustion vconditions therein.

' reach the interior of each piece of material. The

folding back of the outer layers of the material causes the body of each piece to raise off the bed of the furnace allowing the flame hitting the furnace bed to flow under and heat the undersides of the pieces; and thus the heat of the fiame acts on every surface both interior and exterior of each piece. Likewise the intumescence by virtue of popping is insured and carried to completion by the same complete enshroudment of the particle by fiame.,V Y

The intumescent material is carried by the travel ofthe 'furnace bed before blowers 'I2 arranged adjacent the end wall-14 Yof the housing and is gently blown out of the furnace through the delivery spouts 16. Any dust or ash lighter than the body of theV exfoliated material is blown upwardly `and withdrawn. through the vertical flues`18 through which a gentle fiow of air is maintained by cyclones (not shown). 1

To ensure that no powerful suction is set up by .the cyclones, I preferito arrange each flue 7B -to terminate under a hood spaced from the flues 18.-

By the furnace arrangement described and the control of the heating names applied to the material and the manner in which the material is subjected thereto, I am enabled to fully exfoliate perlite and similar material in .an economical manner, and to process such ores 'successfully even when varying considerably in characteristics.

It is pointed out that mechanical means may be utilized to remove the expanded product from the furnace if deemed preferable, or a combination of both air and mechanical means. It`will be noted that since kthe fiames in the furnace impinge against the 'furnace bed resulting in mushrooming of the fiames over the bed, the spaced lpieces of ore as they are carried under the spaced burners are acted upon by the flames on all sides, as well as the upper surfaces. As the pieces raise from the bed by the unfolding of the bottom edges of the pieces, or by the popping of the particle the flames penetrate under the material, this ame action causing a complete intumescence of the material.

While I have described a preferred manner of carrying out my process and suitable apparatus therefor, it is to be understood that various changesand modifications of both thev described process andapparatus may be effected by those skilled in the art Without departing from the scope of the invention as intended to be defined by the appended claims.

Iclaim:

1. In a furnace for effecting intumescence of perlite and other ores having similar characteristics said furnace having an annular imperiorate and rotatable furnace bed and a housing extending over said bed, means to position a plurality of pieces of material simultaneously and in spacer relation to one another on said furnace bed comprising: a drum-like member having a series of spaced pockets formed in its periphery and adapted to receive pieces of ore of substantially the same size; means effective to rotate the drum; tubular guides into which the pieces of ore carried by the drum-like member are delivered by the rotation of the said member and effective to guide the pieces of ore into position in spaced relation upon the furnace bed, and means to direct a flame downwardly upon and around each piece of the ore and upon the furnace bed and by lateralspreading vof the flame perlite and other ores having similar characteristics said furnace having an annular imperforate and rotatable furnace bed and a housing extendying over said bed, means to position a plurality of pieces of material simultaneously and in spaced relation of one another on said furnace bed comprising: amovable member having a series of spaced recesses therein; a hopper having the bottom thereof apertured in alignment with the series of recesses in said movable member; and a series of guiding chutes having upper openings aligned with the spaced recesses in the movable member .and delivering pieces lof ore onto the furnace bed in spaced relation; means to move on the furnace bed and raising of each piecerof ore on its out folded outer layers, under the pieces of Ore. Y

2. A furnace as set forth in claim 1 and comprising a manifold for gaseous fuel arranged within the housing and above the furnace bed, a plurality of orifices being provided in the lower face of said manifold to direct the ame downwardly upon the furnace bed and pieces of ore thereon.

3. A furnace as set forth in claim 1 and comprising a manifold for gaseous fuel arranged within the housing and above the furnace bed, a plurality of orifices being provided in the lower face of said manifold to direct the flame downwardly upon the furnace bed and pieces of ore thereon, a group of said orifices being arranged spaced from the remainder thereof to effect vpreheating of the ore at the commencement of its travel through the furnace.v

4. In a furnace for effecting intumescence of said movable member to bring the aligned recesses therein into position to receive pieces of ore from the hopper and to position the filled recesses over the upper ends of the'guiding chutes for delivery of pieces of ore thereinto; and means to direct a flame downwardly upon and around each piece of the ore and upon the furnace bed and by lateral spreading of the flame on the furnace bed and raising of each piece of ore on its out folded outer layers, under the pieces of ore. GEORGE I-I. MCDONALD.

REFERENCES CITED The following references are of record in the file of thispatent:

UNITED STATES PATENTS Number Name Date 718,257 Keyes Jan. 13, 1903 916,393 Dwight et a1 Mar. 23, 1909 951,198- Perkins et al Mar.v 8, 1910 969,927 Wlfley Sept. 13, 1910 1,075,011 Christensen Oct. 7, 1913 1,206,397 Yost et al Nov. 28, 1916 1,436,520 Oliver Nov. 21, 1922 1,455,975 Spencer May 22, 1923 1,634,027 Honigmann et al. June 28, 1927 1,666,656 Honigmann Apr. 17, 1928 1,763,453 Bartling June 10, 1930 1,904,128 Fuller Apr. 18, 1933 1,963,275 Labus June 19, 1934 1,963,276 Miner et al June 19, 1934 1,992,669 Labus Feb. 26, 1935 2,029,524 Denning Feb. 4, 1936 2,151,083 Christensen et al. Mar. 21, 1939 2,174,066 Ahlmann Sept. 26, 1939 2,265,358 Denning Feb. 9, 1941 2,293,549 Keener Aug. 18, 1942 2,379,418 Cover July 3, 1945 2,403,433 Gelbman July 9, 1946 2,424,330 Robertson July 22, 1947 2,430,601 Cleary Nov. 11, 1947 2,456,207 McCoy Dec. 14, 1948 2,501,962 Pierce Mar. 28, 1950 

